Paper vessels, cardboards, etc. also referred to as packaging containers or paper boxes are formed by punching, bending, and mutually pasting the paper which is comprised of, for example, a plurality of paper types or complex materials of paper types and resins or metals other than paper, cardboards, and coating paper. The paper vessels are lightweight, are useful for transportation, and are widely used in many industrial fields such as food industries, electronic parts industries, and automobile related industries.
FIG. 30 is a cross-sectional view schematically showing the relations between a punching die, paper, and a cutting plate in a known punching machine. A punching die 220 is used for punching of paper 100. The punching die 220 is manufactured by: subjecting a veneer board to laser processing along the outer shape, which is to form a paper vessel, and ruled lines for bending; forming penetrating grooves for punching blades 260 corresponding to the outer shape, which is to form the paper vessel, and penetrating grooves for ruled-line depressing members 250; and embedding the punching blades 260 and the ruled-line depressing members 250 in the respective penetrating grooves. The height dimensions of the ruled-line depressing members 250 are set to be smaller than those of the punching blades 260, and the downward projecting distances of the ruled-line depressing members 250 are the projecting distances smaller than those of the punching blades 260. When the paper 100 is to be punched by an outer-shape line as symbol 101 for forming the paper vessel and scores 102 are to be formed thereon, the scores 102 are formed, and the paper is cut at the same time while holding the paper 100 by rubber members 265 disposed on the punching die 220 so that the paper is not moved. A facing plate 270 is also referred to as a counter plate, is made of plastic such as ABS, PBT, PPS, or a Phenol resin, is comprised of a plate-like, a sheet-like, or a film-like substrate, and is manufactured by processing grooves 271 by cutting at the positions corresponding to the ruled-line depressing members 250 of the punching die 220 by an NC processing machine according to CAD data for manufacturing the punching die 220 and removing the substrate so that the parts which are to abut the punching blades 260 serve as outer peripheries.
In FIG. 30, the punching die 220 is attached to an upper surface plate 191 side of the punching machine. The facing plate 270 is pasted onto a cutting plate 240 and receives the paper 100. Then, the cutting plate 240 is attached to a lower surface plate 192 side of the punching machine, for example, by being mounted on an unshown chase like as frame and receives blade tips of the punching blades 260 disposed on the punching die 220. Then, the paper 100 is inserted between the blade tips of the punching die 220 attached to the upper surface plate 191 of the punching machine and the facing plate 270 on the cutting plate 240 attached to the lower surface plate 192 of the punching machine, and punching is carried out by moving up the lower surface plate 192 and then moving down the lower surface plate 192 (see FIG. 30). More specifically, the paper 100 is cut into a predetermined shape as the locations of the symbols 101 by the punching blades 260, the plurality of scores 102 are engraved on required parts by the ruled-line depressing members 250 and the groove parts 271 of the facing plate 270, thereby forming a blank of punched paper 100. Then, a paper vessel is assembled by valley-folding the blank of punched paper 100 along the scores 102 and mutually pasting bonding margins thereof. Other than that, in addition to the above description, there is a configuration of punching the paper 100, in which perforations which are to serve as a zipper are formed, and forming scores and perforations by incising blades provided on the punching die 220 although not shown in the drawing. FIG. 30 employs a disposition configuration in which the punching die 220 is in the upper side and the cutting plate 240 is in the lower side; however, there is also a case employing a disposition configuration in which the cutting plate 240 is in the upper side and the punching die 220 is in the lower side.
In the above described punching, one blank of punched paper 100 is sometimes formed by one operation. However, in order to enhance productivity, it is preferred to form a plurality of blanks of punched paper 100 at the same time. For example, FIG. 32 exemplifies a known punching die 220 in a state in which the blade tips of punching blades 260 are in the front side, and FIG. 33 exemplifies a known cutting plate 240 in a state in which facing plates 270 are in the front side. In the configuration examples shown in FIG. 32 and FIG. 33, four blanks of punched paper 100 are formed at the same time by one operation.
In order to evenly punch the above described blank, particularly, each of the above described plurality of blanks, the pressing force of the punching die has to be set so that the pressing force is evenly applied to the paper. However, problems in terms of maintenance, time-course changes, etc. are causes that generate unevenness in the pressing force of the punching die. Therefore, in order to evenly punch each of the above described blanks, various efforts for decreasing the pressing-force unevenness of the punching die have been made.
Conventionally, it is known that unevenness is generated in the pressing force due to variations in the lengths of a plurality of punching blades or ruled-line members disposed on a punching die, and a below method is known as a method of removing the unevenness in this case. FIG. 30 is a cross-sectional view schematically showing the relations of unevenness removing paper, the punching die, the paper, and the cutting plate. FIG. 31 is a perspective view showing known unevenness removing paper from an oblique lower side. In the configuration example shown in FIG. 30, the cutting plate 240 is disposed on an upper surface 192a of the lower surface plate 192 of the punching machine, a backing metal plate 221 is disposed between the back side (the upper side in FIG. 30) of the punching die 220 and the upper surface plate 191 of the punching machine, and the unevenness removing paper 230 is disposed between the back side (the upper side in FIG. 30) of the backing metal plate 221 and a lower surface 191a of the upper surface plate 191 of the punching machine. The above described unevenness removing paper 230 increases the pressing force of the punching blades 260 and the ruled-line members 250 by locally pasting and laminating commercially-available adhesive tapes 239 on one sheet of thin paper 238 comprised of, for example, paper or resin on which the drawing shape of the punching die 220 is drawn and increasing the volume thereof, thereby removing the unevenness (see FIG. 31). Then, dummy paper is set and subjected to trial punching, or the actual paper 100 is subjected to trial punching; and an unevenness removing operation of the punching die is carried out by pasting the commercially-available adhesive tapes 239 onto corresponding parts while observing the appearance of the punched paper or dents formed on the unevenness removing paper 230 caused by collision with the punching blades 260 and the bottom surfaces of the ruled-line members 250.